Wetting system for rotary offset printing presses

ABSTRACT

To improve uniformity of supply of moisture to the plate cylinder of a rotary offset printing press, the wetting system comprises two rollers which have surfaces capable of being coated by ink, one of the rollers, in engagement with the plate cylinder, having a rubber-type, yielding surface, the other having an unyielding surface, the other, or transfer roller being axially reciprocating and being driven at a speed to have approximately the same circumferential speed as that of the plate cylinder, the two rollers and the plate cylinder being in such relative pressure engagement that the transfer roller deforms the yielding surface of the former roller in engagement with the plate cylinder, thus decreasing its circumferential speed, the form roller slightly slipping with respect to the plate cylinder to effect cleaning action, while proving transfer of moisture to the plate cylinder, the moisture being supplied in the form of an emulsion of wetting liquid and ink, which will form on the surface of the form roller, in engagement with the plate cylinder.

llnited States Patent [191 Fischer 1 Sept. 2, 1975 [54] w Tn SYSTEM FOR ROTARY F ET 3,467,008 9/1969 Domotor 101/148 3,508,489 4/1970 NOTIOIIW. l0l/l48 3,552,311 1 1971 Petri 101 148 [75] Inventor: Hermann Fls h ug u g, 3,561,357 2 1971 Schinke 101/148 Germany FOREIGN PATENTS OR APPLICATIONS [73] Asslgnee Maschmenfabnk 678,543 7/1939 Germany 101/148 Augsburg'Nul'nberg Augsburg 488,444 7/1938 United Kingdom 101/148 Germany [22] Filed: Dec. 6, 1974 Primary ExaminerJ. Reed Fisher Appl. No.: 530,156

Related U.S. Application Data [30] Foreign Application Priority Data Apr. 29, 1972 Germany 2221289 [52] U.S. Cl 101/148; 101/148 [51] Int. Cl. B41F 7/26; B41F 7/40 [58] Field of Search 101/147, 148, 349-352, 101/206209 [56] References Cited UNITED STATES PATENTS 2,103,254 12/1937 Goedike lOl/l48 2,238,050 4/1941 Goedike..... lOl/148 2,622,521 12/1952 Larsen 101/148 2,690,119 9/1954 Black 101/148 2,733,654 2/1956 Rogers lOl/l48 3,096,710 7/1963 Wojciechowski. 101/148 3,146,706 9/1964 Tonkin et a1. lOl/l48 3,168,037 2/1965 Dahlgren 101/148 3,405,636 10/1968 Schmidlin 101/148 3,455,238 7/1969 Gambella et al 101/148 Attorney, Agent, or FirmFlynn & Frishauf ABSIRACT To improve uniformity of supply of moisture to the plate cylinder of a rotary offset printing press, the wetting system comprises two rollers which have surfaces capable of being coated by ink, one of the rollers, in engagement with the plate cylinder, having a rubbertype, yielding surface, the otherhaving an unyielding surface, the other, or transfer roller being axially reciprocating and being driven at a speed to have approximately the same circumferential speed as that of the plate cylinder, the two rollers and the plate cylinder being in such relative pressure engagement that the transfer roller deforms the yielding surface of the former roller in engagement with the plate cylinder, thus decreasing its circumferential speed, the form roller slightly slipping with respect to the plate cylinder to effect cleaning action, while proving transfer of moisture to the plate cylinder, the moisture being supplied in the form of an emulsion of wetting liquid and ink, which will form on the surface of the form roller, in egagement with the plate cylinder.

13 Claims, 5 Drawing Figures WETTING SYSTEM FOR ROTARY OFFSET PRINTING PRESSES The present application is a continuation-in-part of prior application Ser. No. 353,525, filed Apr. 23, 1973, now abandoned.

The present invention relates to rotary offset printing machines and more particularly to the moisture supplying apparatus, which is separate from the inking mech anism. and in which the supply of moisture is accurately controlled.

It is well known that the quality of offset printing is largely dependent on the moisture supply. The quantity of wetting or moisture supplying substances is very low. The moisture substance must be supplied to the printing plate, or cyliner, while being uniformly distributed. Uniformly distributing this small supply still presents difficulties, particularly if the plates carry only little printed subject matter, or on which the subject matter to be printed is unevently distributed.

One of the solutions to this problem (see Swiss Pat. No. 428,783) was to utilize a moisture transfer roller with a surface capable of accepting water, to supply water to this surface, and permitting a form roller in engagement with the moisture transfer roller to roll off the plate cylinder, so that ink corresponding to the subject matter to be printed will be accepted thereby. The ink layer is not continuous, however; it is, therefore, not distributed uniformly on the surface of the form roller, so that the wetting substance is not accepted uniformly over the entire length of the roller in equal, uniform manner, and transport thereby.

It is an object of the invention to improve the moisture supplying apparatus for rotary offset printing press in such a manner that the supply of moisture is uniform, and in which striping, and hence poor printing, are avoided.

SUBJECT MATTER OF THE PRESENT INVENTION A form roller is arranged adjacent the plate cylinder, to be freely rotatable. It is formed with a surface which is yeilding and capable of accepting ink. A transfer roller is in engagement with the form roller and has a con tinuous, unyielding surface capable of accepting ink. Wetting liquid is applied to transfer roller. The surfaces of the form roller and of the transfer roller are continuously coated with ink. In operation, the wetting liquid will be applied on the continuous ink layer derived, at least in part, from the plate cylinder. The transfer roller is driven with approximately the same circumferential speed as the plate cylinder. A pressure adjusting device is provided to adjust the engagement pressure between the plate cylinder, the form roller, and the transfer roller. the adjustment being so made that some slip will obtain between the plate cylinder and the form roller, that is, that the transfer of rotary power from the transfer roller to the form roller is greater than the transfer of rotary movement from the plate cylinder to the former roller.

The transfer roller is axially oscillating, or reciprocating. lnk derived from the plate cylinder is uniformly distributed on the axially reciprocating transfer roller, and hence on the form roller, so that any remanent ink from the subject to be printed is transferred continuously by the engagement with the transfer roller thereto, and uniformly distributed due to the axial reciprocation thereof. The coating of ink which, then, results on the axially reciprocating transfer roller controls the drive of the form roller so that, contrary to prior practice, the form roller is driven from the axially reciprocating transfer roller due to its entire, continuous cover with ink, rather than from the plate cylinder which has an interrupted ink coating (depending on the subject matter to be printed). The adjustment of friction between the form roller and the axially reciprocating or oscillating transfer roller, and the relative surface characteristics (a hard, unyielding surface on the reciprocating transfer roller and a yielding surface on the form roller) result in a kneading action on the surface of the form roller. The circumferential speed thereof, hence, is delayed so that differential surface speeds between the form roller and the plate cylinder will result, such that the form roller is delayed or has a slower speed than the plate cylinder.

The differential speed of the plate cylinder and the form roller has a cleaning effect on the plate cylinder. Zones or regions on the plate cylinder which might cause toning, that is, surfaces which should be moist but on which ink has been deposited are cleaned in that the toning or ink deposits at those regions or zones are rapidly removed. Equilibrium condition between ink and wetting liquid (typically water) will rapidly and au tomatically arise. Balance of ink and water on the plate, for perfect printing results, will be automatically acheived, An emulsion of ink and water is transferred, rather than pure water, and thus contamination of the inking system by wetting liquid is prevented. The deposit of wetting liquid in the inking system is effectively inhibited. The film of ink which is transferred, indirectly, to the reciprocating transfer roller from the region to be printed, on the plate, additionally increases friction within the wetting system, so that slip of the respective rollers is prevented if there is a change in operating speed of the press. Thus, better control over the quantity of wetting liquid being applied can be ob tained. It is much easier to transfer wetting liquid to the plate in small quantities by applying the wetting liquid to a roller coated with ink in this case the transfer roller than directly from a wetting roller which is immersed in, or has wetting liquid applied thereto and which only accepts water. The film of ink on the reciprocating cylinder is uniformly distributed thereover due to firctional engagement and the axial reciprocation and thus the film of wetting liquid applied thereover can be very thin, and additionally will be uniform. Its further transfer to the plate cylinder over the form roller then will accurately control the quantity of wetting liquid being applied to the plate cylinder. Any remnants of ink remaining on the plate are smoothed by the wetting liquid on form roller. Due to the separation of wetting system and inking system, and the differential speeds, any remnants of ink which previously were carried back to the first inking rolller (where they resulted in a non-uniform inking) are removed, or at least attenuated to prevent over-inking. The separation of the inking system, and the wetting system, and the arrangement of the rollers, as aforesaid, prevents penetration of wetting liquid into the inking system. This also decreases the consumption of wetting liquid and permits better control of the quantity thereof being applied to the plate cylinder.

The axially reciprocating transfer cylinder preferably has a hard surface; a plastic material capable of accepting ink of the type of nylon known under the trademark RILSAN is suitable. The surface may also be formed of copper, particularly if there is little tendency to form acids.

The form roller has a surface made of a resilient material, having rubbery characteristics; a composition material made of rubber with approximately 30% plas tic additives, to improve its stability and shape retention, is suitable. The characteristics which the form roller must have are softness, smooth surfaces, shape retention, and resistance to abrasion.

The invention will be described by way of example with reference to the accompanying drawings, wherein:

FIG. 1 is a highly schematic view of a fraction of a plate cylinder, a portion of the inking system, and the wetting system in accordance with the present invention;

FIG. 2 is a schematic illustration of the drive for the wetting system; and

FIGS. 3, 4 and 5 illustrate various embodiments and variations of the wetting system in accordance with the present invention.

Ink is applied to the plate cylinder 1 (FIG. 1) over inking rollers 2, which receive ink from a reciprocating ink supply roller 3. The inking system, itself, is not shown in greater detail and may be of any standard and well-known type. The inking rollers apply ink to those zones or portions of the plate cylinder 1 for transfer to the rubber cylinder, as customary in offset printing, for subsequent application to the material to be printed, for example to a paper web.

A wetting system, separate and independent of the inking system is provided in order to supply wetting liq uid, typically water, to the surfaces of the plate cylinder 1 which are to be wetted. The separate wetting system has a form roller 5, in engagement with the plate cylinder 1; an axially reciprocating or oscillating transfer roller is in contact with form roller 5. A wetting liquid tray is provided in which a wetting liquid transfer roller 12 is partially immersed, transporting wetting liquid to the axially reciprocating transfer roller 10. The specific way in which wetting liquid is transferred from the trough, and hence from roller 12 to the transfer roller 10 will be described in connection with the specific description of the various Figures.

The surface of form roller 5 is yielding; it has the properties of rubber, that is, it has rubbery characteristics, capable of accepting ink, and extending throughout the entire axial length of the roller 5. Roller 5 is freely rotatable in end bearings. The transfer roller 10 has an unyielding, continuous surface capable of accepting ink. It is in frictional contact with former roller 5. The transfer roller 10, which may be also termed a wetting liquid friction roller, is positively driven in synchronism with the drive from the plate cylinder, and has approximately the same circumferential speed. Although the plate cylinder 1 is only partially covered with subjects requiring inking, the surfaces of the liquid form roller 5 and the liquid friction roller 10 are completely and uniformly coated by ink due to the substantial differences in diameters between rollers 5 and 10 on the one hand, and plate cylinder 1 on the other. This difference in diameter provides for a plurality of revolutions of rollers 5 and 10 for each revolution of plate cylinder 1. Thus, the entire surface of the form roller 5 is coated with ink. The surface of the wetting friction transfer roller 10 preferably is a plastic material capable of accepting ink, or copper. The form roller 5 engages the plate cylinder 1 with pressure; it is also engaged, with pressure, by the reciprocating wetting friction transfer roller 10. The pressure is adjustable, for example by mounting the bearings for roller 5 in an eccentric opening. The force with which the roller 5 is driven thereby can be adjusted. This force will depend on the viscosity, deformability, adhesive properties, and other characteristics of the ink; the respective diameters of the rollers (due to the difference in cantact areas between rollers of large and small diameter). The force with which roller 5 is carried along thus depends on the pressure with which it is engaged, respectively, by the plate cylinder 1, and the transfer roller 10, as well as ink characteristics, and is adjustable. The force is so arranged that the form roller 5 has a cleaning effect on the plate cylinder 1; in order to obtain this cleaning effect, that is, to have form roller 5 operate with respect to plate cylinder 1 with slip, the respective pressures of engagement are so selected that the engagement pressure of form roller 5 with the axially reciprocating roller 10 is greater than the engagement pressure of form roller 5 with plate cylinder 1. The operating speed of the form roller 5 is thus commanded not by the plate cylinder 1, but rather by the axially reciprocating friction roller 10. Friction roller 10 operates with approximately the same circumferential speed as the plate cylinder 10; however, since the distances between the centers of the shafts of the rollers 5 and 10 are selected to be slightly smaller than the sum of the radii if the rollers are out of engagement, a kneading action will result, due to depression of the yielding surface of the form roller 5 by the unyielding surface of axially reciprocating friction roller 10. This kneading action, due to the yielding surface of form roller 5, and the viscosity, consistency, and characteristics of ink on the completely inked surfaces of form roller 5 and friction roller 10 cause a decrease in the circumferential speed of the form roller 5 with respect to that of the plate cylinder 1. Form roller 5, therefore, at the engagement surface with plate cylinder 1 will have a slightly smaller circumferential speed, resulting in slip. This slip removes any striping or remnants of ink on the plate cylinder.

FIG. 1 illustrates an example to adjust the engagement pressures of the form roller 5 with respect to the plate cylinder 1 and to the reciprocating friction transfer roller 10. Roller 5 is journalled in center bearings 21, located in one arm lever 22. The fulcrum of the one arm lever is the axis of the axially reciprocating transfer roller 10. The lever 22 is formed with a lateral projection, or shoulder 23, which bears against an eccenter 24, being held thereagainst under the force of a spring 25 which is supported by a bracket 25, secured to the frame of the machine (not shown) and, with its other end, exerting pressure on the lever 22. By rotating eccenter 24, the engagement pressure of form roller 5 with respect to plate cylinder 1 can be adjusted. Upon rotating the eceentrically located bearings 21, in which the form roller 5 is journalled, the relative pressure between the form roller 5 and the engaging oscillating roller 10 can be changed, so that the force with which form roller 5 is driven by the driven roller 10 is adjustable, such that this force is greater than the engagement force between form roller 5 and plate cylinder 1, resulting in the aforementioned slip with respect to plate cylinder 1.

The axially reciprocating friction roller is driven by a gear 30 (FIG. 2) secured to the shaft of the plate cylinder 1; an intermediate gear 31 transfers rotary movement to gear 32 secured to the shaft of roller 10. The form roller 5, as above noted, is not separately, positively driven, but is driven by engagement with the oscillating roller 10. The wetting pick-up roller 12 is separately driven by a suitable belt, chain or gear drive, schematically shown as a belt .34, from an individual motor 33 (FIG. 2). Rollers ll, 13 and 14 are driven by frictional engagement with roller 10. The circumferential speed of wetting liquid pick-up roller 12 is much less than that of the oscillating friction roller 10.

The cleaning effect is obtained in combination with the wetting liquid supplied from the trough and liquid supply roller 12 and transported to the transfer roller 10 and hence on the form roller 5. It is necessary that the form roller 5 have a film of wetting liquid applied thereto. This film is pressed into the surface, due to the pressure relationship between the associated, adjacent rollers, so that the film will be pressed into the ink and there form an emulsion, to be transported as an emulsion to the plate cylinder ll. Transfer of only minute quantities of wetting liquid to the plate is possible thereby, and is much simpler by transfer in the form of an emulsion from previously inked rollers which are part of the wetting system than transfer from a wetting system which is solely capable of transporting water, that is, which is only hydrophilic. The oscillating friction transfer roller 10 is, preferably, additionally engaged by rollers 13, 14 which are compensating rollers. The liquid transfer roller 12 preferably has a chrome surface; liquid transfer roller ll preferably has a rubber surface, so that wetting liquid is transferred from the trough to roller 12, roller 11, and then to the ink coating on roller 10.

The wetting system basically has, then, a freely rotatable form roller 5, and a driven, axially reciprocating friction wetting roller 10, both rollers 5 and 10 having surfaces capable of accepting ink. This portion of the system is the same for all the embodiments; the application of wetting liquid to the roller 10 may be different, however. As seen in the embodiment of FIG. 3, the wetting liquid is sprayed from a spray system 15 on a transfer roller 20, to be applied to roller 10. Alternatively, the spray system 15 may directly apply wetting liquid to the reciprocating friction transfer roller 10. The spray system 15 may consist of fixed nozzles, slinger disks, or the like. Ink is applied to the friction roller 10 not only as previously explained, but may additionally be applied by coating an ink application roller 4- with ink, roller 4 being in engagement with roller 10. Thus, rollers 5 and 10 can be pre-inked before starting the machine in operation. This form is particularly suitable if the material to be printed, throughout the lateral extent of the printed material, has wide divergencies in subject matter requiring ink, so that uniformity of the ink coating on the rollers 5 and 110 is ensured immediately upon operation of the machine.

Embodiment of FIG. 4: The chrome-surface wetting liquid roller 12 is in immediate engagement with the reciprocating friction transfer roller 10. A roller 17 is provided to initially pre-coat roller 10 with ink (similar to roller 4, FIG. 3). To provide for control of the quan tity of wetting liquid being applied to roller 10., roller 12 can be radially oscillating, in and out of engagement, with roller 10 or, similarly, a separate control roller l8 may be provided, which splits off, or strips off excess liquid being applied by roller 12 to roller 10.

Embodiment of Flg. 5: Wetting liquid is applied to the reciprocating friction roller 10 by means of a duetor roller l9 which intermittently is engaged with the hydrophilic roller 12 and roller 10, respectively. Ductor 19 preferably has a surface or rubber, or rubbery material, having the characteristics of rubber. Roller l3 corresponds to roller 13 in FIG. 1 or may be used to pre-coat roller (similar to rollers 4, 17, FIGS. 3 and 4). Roller 13 is selectively in and out of engagement with roller 10, as schematically indicated by separation of the circumference thereof from roller 10. Roller 13 is not strictly necessary and is therefore shown in dashed lines.

The present invention is not limited to the wetting systems described, but can be used with any wetting system in which at least two rollers are provided having surfaces which are capable of accepting ink and are, in fact, in operation coated with ink, one of the rollers (roller 10) having wetting liquid applied thereto which is transferred to a form roller, to be there formed into an emulsion of ink and wetting liquid, to transfer wetting liquid to the plate cylinder, so that the plate cylin der will be supplied with the appropriate quantity of wetting liquid. More than one roller of the type of rol lers 5 may be used, arranged in series, or in parallel thereto with respect to roller 10 and plate cylinder 1, and transferring wetting liquid, in form of an emulsion of ink and wetting liquid, the roller actually in engagement with the plate cylinder additionally having slip to clean the surface thereof. The diameter of the transfer roller 10 preferably is selected to be larger than the diameter of the roller with the yeilding surface, that is, roller 5.

Various changes and modifications may be made, and features described in connection with any one of the Figures may be used with any one of the others, within the inventive concept.

I claim: 1. Rotary offset printing press having an inking system (2, 3), wetting liquid feed means (ll, 12, 15, 20; 19) and a wetting system to transfer moisture from the wetting liquid feed means to the plate cylinder (ll) of the press, wherein the wetting system comprises two rollers (5, l0) transferring wetting liquid to the plate cylinder (ll),

one of the rollers (5) being a form roller and freely rotatable, and having a surface with is smooth, yielding and capable of accepting ink,

the other of the rollers (10) having a surface which is unyielding, continuous, and capable of accepting ink,

said two rollers (5, 10) being relatively located with respect to each other to be in rotation transmitting engagement, said rollers, in operation, having a continuous ink layer deposited thereon and a layer of moisture derived from the wetting liquid pick-up means;

drive means (30, 31, 32) driving the other, or trans fer roller (10) in synchronism with the plate cylinder at a circumferential speed approximately simi lar to the circumferential speed of the plate cylinder (1 and means (21, 22, 23, 24; 25, 26) acting on the shafts of the rollers effective to provide for and adjust engagement pressure between the first, or form roller with respect to the plate cylinder (1) and the engagement pressure between the second, or transfer roller and the form roller (5), said pressure adjusting means being set to provide a greater engagement pressure between said two rollers (5, 10) than between the form roller (5) and the plate cylinder (1), so that the surface of the form roller (5) will be deformed by the transfer roller (10) resulting in slightly lower circumferential speed of the form roller (5) than of the transfer roller, and hence of the plate cylinder, and provide for slip between the plate cylinder (1) and the form roller (5).

2. Press according to claim 1, wherein the transfer roller 10) has a diameter which is greater than the diameter of the form roller (5).

3. Press according to claim 1, wherein the transfer roller (10) is axially reciprocating.

4. Press according to claim 1, wherein the wetting liquid feed means comprises a wetting liquid roller (12) within a trough, having a chromed surface, and transferring wetting liquid to the second roller (10).

5. Press according to claim 1., wherein the second, or transfer roller (10) has a surface of ink-accepting plastic material.

6. Press according to claim 1, wherein the second, or transfer roller (10) has a surface of copper.

7. Press according to claim 1, further comprising an intermediate roller (11) having a rubber-type surface and located between the second, or transfer roller (10) and the wetting liquid feed means.

8. Press according to claim 1, further comprising an ink application roller (4, 17). at least in intermittent engagement with the second or transfer roller (10).

9. Press according to claim 1, wherein the wetting liquid feed means comprises spray means (15) and a liquid transfer roller (20) exposed to the spray from the spray means, and in liquid transfer relation to the second, or transfer roller (10).

10. Press according to claim 1, wherein the wetting liquid feed means comprises a liquid pick-up roller (12), and a liquid control roller (18) in engagement with said liquid pick-up roller.

11. Press according to claim 1, wherein the liquid feed means comprises a ductor roller (19) in intermittent engagement between a liquid pick up roller (12), and the second, or transfer roller.

12. Press according to claim 1, wherein the inking system and the wetting system are separate from each other.

13. Press according to claim 1, wherein the liquid feed means comprises spray means (15) directly applying wetting liquid to the second, or transfer roller (10). l =l 

1. Rotary offset printing press having an inking system (2, 3), wetting liquid feed means (11, 12, 15, 20; 19) and a wetting system to transfer moisture from the wetting liquid feed means to the plate cylinder (1) of the press, wherein the wetting system comprises two rollers (5, 10) transferring wetting liquid to the plate cylinder (1), one of the rollers (5) being a form roller and freely rotatable, and having a surface with is smooth, yielding and capable of accepting ink, the other of the rollers (10) having a surface which is unyielding, continuous, and capable of accepting ink, said two rollers (5, 10) being relatively located with respect to each other to be in rotation transmitting engagement, said rollers, in operation, having a continuous ink layer deposited thereon and a layer of moisture derived from the wetting liquid pick-up means; drive means (30, 31, 32) driving the other, or transfer roller (10) in synchronism with the plate cylinder at a circumferential speed approximately similar to the circumferential speed of the plate cylinder (1); and means (21, 22, 23, 24; 25, 26) acting on the shafts of the rollers effective to provide for and adjust engagement pressure between the first, or form roller (5) with respect to the plate cylinder (1) and the engagement pressure between the second, or transfer roller (10) and the form roller (5), said pressure adjusting means being set to provide a greater engagement pressure between said two rollers (5, 10) than between the form roller (5) and the plate cylinder (1), so that the surface of the form roller (5) will be deformed by the transfer roller (10) resulting in slightly lower circumferential speed of the form roller (5) than of the transfer roller, and hence of the plate cylinder, and provide for slip between the plate cylinder (1) and the form roller (5).
 2. Press according to claim 1, wherein the transfer roller (10) has a diameter which is greater than the diameter of the form roller (5).
 3. Press according to claim 1, wherein the transfer roller (10) is axially reciprocating.
 4. Press accordiNg to claim 1, wherein the wetting liquid feed means comprises a wetting liquid roller (12) within a trough, having a chromed surface, and transferring wetting liquid to the second roller (10).
 5. Press according to claim 1, wherein the second, or transfer roller (10) has a surface of ink-accepting plastic material.
 6. Press according to claim 1, wherein the second, or transfer roller (10) has a surface of copper.
 7. Press according to claim 1, further comprising an intermediate roller (11) having a rubber-type surface and located between the second, or transfer roller (10) and the wetting liquid feed means.
 8. Press according to claim 1, further comprising an ink application roller (4, 17), at least in intermittent engagement with the second or transfer roller (10).
 9. Press according to claim 1, wherein the wetting liquid feed means comprises spray means (15) and a liquid transfer roller (20) exposed to the spray from the spray means, and in liquid transfer relation to the second, or transfer roller (10).
 10. Press according to claim 1, wherein the wetting liquid feed means comprises a liquid pick-up roller (12), and a liquid control roller (18) in engagement with said liquid pick-up roller.
 11. Press according to claim 1, wherein the liquid feed means comprises a ductor roller (19) in intermittent engagement between a liquid pick up roller (12), and the second, or transfer roller.
 12. Press according to claim 1, wherein the inking system and the wetting system are separate from each other.
 13. Press according to claim 1, wherein the liquid feed means comprises spray means (15) directly applying wetting liquid to the second, or transfer roller (10). 